Shellac modified resin



Patented July 30, 1946 2,404,892

UNITED STATES PATENT OFFICE SHELLAC MODIFIED RESIN Milton J. Scott, Stamford, Conn, assignor to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application February 28, 1942,

Serial No. 432,733

11 Claims; (Cl. 26024) 1 2 v This invention relates to the prod of slowly to about 90 C. The molar ratio of aniline thermosetting resins of the aromatic amine-aldeto formaldehyde is 1:1. In its initial stage, the e type and is more particularly concerned with reaction is strongly exothermic and the temperaaniline formaldehyde resins. ture control is necessary. After the reaction is s pplication is in part a continuation of .5 no longer strongly exothermal, an acid catalyst an application Serial No. 421,484 filedDecembe containing 0.7 part concentrated sulfuric acid in 3, 1941, by Schroy, Grabowski and Scott, now 18 parts water is added. The mixture is then Patent 0. ,33 3 dated November 6, 1945. heated to reflux and held at that temperature for The joint invention of Schroy, Grabowski and about 1% hours. The reaction product is cooled myself, as 'set forth in the specification and claims 10 to about 70 C. and vacuum concentrated at 20 /2 f e patent referred to above, relates to mixinches of mercury until the temperature reaches tures of triazine-formaldehyde resins and aro- 165 C. At this temperature, the vacuum is raised matic amine-aldehyde resins including shellacto 27-28 inches and concentration continued until modified aromatic amine-aldehyde esi moldthe temperature reaches 120 C. After which the ins comp i ns comprising s ch res ous l resin is poured into trays Or the like and allowed tures, and p o s for preparing the molding to cool. The cooled resin is preferably ground compositions. Invention of the shellac-modified and may then be subjected to such further operaaromatic amine-aldehyde resinous compositions tions as may b ired. Th esin i a fusible p 8 and their method- Of manufacture, as solid having a melting point of about 74 C. scribed and claimed in the present case, was made 20 EXAMPLE 2 solely by me. Parts The aromatic amine-aldehyde resin such as Aniline 758 aniline-formaldehyde, are essentially of the non- Formalin (37% formaldehyde) 662 heat-setting type. Various expedients have been Concentrated sulfuri acid 43 suggested to bring about polymerization of these Water 120 resins to the infusible state but the proposed T methods have met with generally indifferent suc- This resin is prepared in the same manner as cess. The aniline-formaldehyde resins previously described for the resin in Example 1 eXcept th described are all essentially thermoplastic and Since 110 Shellac is used, the initial s p of eactnot thermosetting. ing the shellac with the aniline is omitted. After I have found that the addition of shellac to the e r sin is f rme there is added 1% to 25% of amine-aldehyde resin at some time prior to the shellac, based on the weight of aniline used. The final polymerization step permits the formation shellac may be reacted by mixing it with the hot, of a fusible resin which becomes infusible upon molten resin as it come from the processing or heating. My resin compositions belong to the 5 it may be added at any subsequent time by reclass of thermosetting resins. The shellac may melting the resin and dissolving the shellac in be added during the preparation of the aminethe molten mass. The resultant fusible resin is aldehyde resin or may be added to the fusible substantially identical with that prepared in acresin after it is formed. In order to obtain best cordance with Example 1. fusing and curing properties, it is preferable that EXAMPLE the molar ratio of aldehyde to amine be above about 3:4.

The following examples are given for purposes of illustration and not in limitation, the parts being given by weight unless otherwise stated. 45

A resin wherein the ratio of formaldehyde to aniline i 2.15:1, may be prepared in the same manner as described in Example 1, utilizing the following ingredients:

. Parts EXAMPLE 1 Aniline 147 Shellac 49 A mixture of 30 parts shellac and parts amline is heated at a temperature of about 0., g' g} 2 afifi ig with agitation, until the shellac and aniline are 50 $2 5 ed 5 no 29 reacted and a homogeneous composition is oba el "T ff' tained. The solution is cooled to room tempera- There is obtained a fusible resin of the same genture and 79.0 parts of formalin (37% formaldeeral nature as that of Example 1, except that the hyde by weight) is added slowly with agitation,the resin here prepared has a melting point of about mixture being cooled so that the temperature rises 101 C.

EXAMPLE 4 Parts Aniline 78 In-P-Cresol 30 Formaline (37% formaldehyde) 90 Concentrated sulfuric acid 0.6 Water 14 A resin is prepared from the above ingredients following the procedure given in Example 1 except that the cresol is added to the. aniline in place of shellac and since solution is immediately obtained, the heating step for reacting the shellac is unnecessary. The resin obtained, while still in the molten condition, may be mixed with 1% to of Shellac based on the aniline, or the shellac concentration continued until the temperature reaches 120 C. after which the resin is poured into trays or the like and allowed to cool. The cooled' resin is preferably ground and may then be subjected to such further operations as may may be added subsequently to the remolten resin.

In order to obtain thermo-setting of the aniline resins described, the final ratio of formaldehyde to aniline should be at least 2:1. Where the resin does not contain suflicient aldehyde, the deficiency should be made up before final polymerization and setting is attained. Under these conditions, the resin prepared in accordance with Example 1, when mixed with about 15% of its weight of paraform prior to curing, will set up to an infusible product in about seconds at 150 C. The resin of Example 3 will set in about seconds at 150 C. without the addition of paraform or other formaldehyde. The resin of Examples 2 and 4, after dehydration and the addition of shel ac also set upin about the same times, with the addition of paraformaldehyde or formaldehyde from some other source.

In place of the paraform suggested for use with these resins, there may be substituted hexamethylenetetramine or another compatible resin containing combined formaldehyde such as ureaformaldehyde, dicyandiamide-formaldehyde, triazine-aldehyde, e. g., melamine-formaldehyde, etc.

Inplace of the sulfuric acid used as a catalyst in the above examples. I may use other inorganic or organic acids singly or in admixture.

Suitable acids include hydrochloric, phosphoric,

sulfamic, trichloracetic, formic, oxalic, etc. Likewise, it may sometimes be advantageous to use compounds or mixtures which develop acid under the conditions of reaction, i. e., acid chlorides, ammonium .salts of strong acids and thelike. In some cases the acid or equivalent substance may be omitted entirely or may be added subsequently. The acid material used, active or la- A mixture of 30 parts of shellac and parts aniline is heated at a temperature of about 120 C., with agitation, until the shellac and aniline are reactedand a homogeneous composition is obtained. Thesolution is cooled to room temperature and 79.0 parts of formalin (37% formaldehyde by weight) is added slowly with agitation, the mixture being cooled so that the temperature rises slowly to about 90 C. The molar ratio of aniline to formaldehyde is 1:1. In its initial stage, the reaction is strongly exothermic ratio of aniline to formaldehyde is 1:1.

- be desired. The resin is a fusible solid having substantially the same characteristics as the resin prepared in accordance with Example 1.

In place of an acidic catalyst, an alkaline catalyst may be used. In order to avoid affecting water resistance of the finished resin, it is preferred to use an alkaline material which is substantially water insoluble. Thus, calcium hydroxide is especially suitable for this purpose.

EXAMPLE 6 A mixture of 30 parts of shellac and 90 parts aniline is heated at a temperature of about 120 (3., with agitation, until the shellac and aniline are reacted and a homogeneous composition is obtained. The solution is cooled to room temperature and'79.0 parts of formalin (37% formaldehyde by weight) is added slowly with agitation, the mixture being cooled so that the temperature rises slowly to about 90 C. The molar In its initial stage. the reaction is strongly exothermic and the temperature control is necessary. After the reaction is no longer strongly ,exothermal, an alkaline catalyst p epared by slaking 0.7 part calcium oxide is added. The'slaked lime in the form of a slurry is referably freshlyprepared just prior to use. The mixture is then'heated to reflux and held at that temperature for about 1 /2 hours. The reaction product is cooled to about 70 C. and vacuum concentrated at 20% inches of mercury until the temperature reaches C. At' this temperature. the vacuum is raised to 27-28 inches and concent at on continued until the temperature reaches C.'after which the resin is poured into trays or the like and allowed to cool. The cooled resin is preferably ground and may then be subjected to such further operations as may be desired. The resin is a fusible solid having substantiall the same characterist cs as the resin prepared in accordance with Example 1.

Other aromatic amines can be substituted for the aniline, e. g., toluidines, diphenyl amines, phenylene diamines and the like. In placeof the formaldehyde. other suitable aldehydes'such as acetalde yde, furfuraldehyde'and the like may be used. The ratio of aldehyde to amine has an active influence on the properties of the resin. With an increase of the aldehyde amine ratio, the melting point of the resin will be found to increase. Thus, as noted in Example 1 where the formaldehydezaniline molar ratio is 1:1, the melting point of the resin is about 74 C., In

Example 3 where the process of production is the same but the molar ratio of formaldehyde to aniline is about 2:1, the melting point of the resin Aniline-formdldehydeeshellac. resins.

. ASTM ball and ring melting'pomt centigrade (average) Molar ratio at iormaldehyderto aniline Degrees The. amount of shellac which is used is not too critical since 1% to 50% of shellac may be used, based on the aniline content. With increasing amounts of shellac,-faster polymerization of the resin is obtained. Even amountsof shellac in excess of 50% will do no harm but merely serve as diluent. When the shellac used represents about A; of the weight 'of the aniline, the rate of cure or polymerization is generally most satisfactory for commercial operation.

The aniline resins of the presentinvention may be compounded with fillers to give heat hardenable molding compositions, the molded products having excellent insulating properties and alkali resistance. The molding compositions may be prepared by incorporating the resin with the filler on the hot differential rolls at temperatures of about 110-1l5- C., in Banbury mills, or in other suitable mechanical mixing devices. Zinc stearate or other suitable lubricant as well as paraform or other desired source of formaldehyde may also be incorporated in the compounding operations.

For the production of molding compositions the resins may be compounded with any of the more commonly used fillers, alone or in admixture. Suitable fillers include cellulose, wood meal, mica, asbestos, celite and the like. These fillers are compounded with the resins to form homogeneous molding compositions. For the production of molding compositions suitable for use in molding articles having high impact strength the resins or molding compositions may be reinforced with such substances as canvas, asbestos, glass or the like, alone or combined in woven or spun form.

The molding compositions prepared as described are useful for molding under heat and pressure using the well-known compression technique. By altering the ratios of aldehyde to amine or by otherwise varying the procedure used for forming the resins, the heat setting properties of the resins may be altered so as to make the molding compositions suitable for transfer molding operations. Thus there are obtained aniline formaldehyde resins which are suitable for use with the quick molding technique using heat and pressure to give a molded article which may be removed from the hot mold without chilling. Due to their thermoplasticity the aniline formaldehyde resins previously available commercially required high pressures for molding and it was also necessary to chill the mold to harden the molded article prior to its removal from the mold. With my resins, by changing the formaldehyde:aniline ratios and/ or by the use of suitable acid catalyzers it is possible. to obtain ireeefiowing compositions of varying degrees of flow. Molding compositions may be prepared to produce perfect homo.- geneous. moldings at pressures of 2000-4000 lbs/sq. in. with sufficiently rapid cure to permit of commercial utilization. Likewise, more freefiowing resins may be obtained which are. suitable for laminating operations wherein. pressures of 800- 0-1bs.-sq..in. are used.

In usingmy resins for the production of laminated articles the conventional laminating technique and conditions are suitable. The laminae may be of paper, asbestos paper, glass or asbestos cloth, canvas or suitablev combinations of these. The resin maybe applied as a solution or in the molten form. Since low melting resins may be. obtained by variations in processing and proportions, as already described, the advantageous fusion technique is preferred since the resin may be applied to the laminae in the molten form, using rolls or the like, or the molten resin may be sprayed upon the surfaces of the laminae. The use of solvents is considered somewhat undesirable since it is necessary to remove the solventbefore laminating and, unless the solvent is recovered, this operation is comparatively less economical than the fusion method. Furthermore, when solvents are used, the laminated product does not have as good electrical properties as is the case when no solvent is used.

The molded articles made with my resins, with or without fillers, etc., are characterized by their outstanding electrical properties. They have a low power factor as well as high are resistance and dielectric strength. The dielectric properties of the molded article change very little with rise in temperature and, as a result, these molded articles are particularly suitable as high voltage insulators. In addition, the molded articles prepared from my compositions have outstanding alkali resistance. The resins of the present invention are obviously susceptible of other uses which will readily suggest themselves. Thus the oil-soluble aniline resins are suitable for the production of surface coating compositions wherein the resins add their desirable properties to the finished coating.

It will be obvious that other changes may be made in carrying out the invention without departing from the spirit and scope thereof as defined in the appended claims.

I claim:

1. The process which comprises reacting an aromatic amine having an NHz group attached to a benzene ring with shellac and, an aldehyde in a molar ratio of at least about mol formaldehyde for each mol of amine until a fusible resin is formed, the shellac used not exceeding 50% by weight of the amine, the resin being thermosetting when it contains about 2 mols combined formaldehyde for each mol of amine.

2. The process which comprises reacting aniline with shellac and an aldehyde in a molar ratio of at least mol formaldehyde for each mol of aniline until a fusible resin is formed, the shellac used not exceeding 50% by weight ofthe aniline, the resin being thermosetting when it contains about 2 mols combined formaldehyde for each mol of aniline.

3. The process which comprises reacting shellac and aniline in a ratio not exceeding 1:2 by weight until a homogeneous composition is obtained, adding formaldehyde in an amount equivalent to at least mol for each mol of amine, reacting this mixture with cooling to pre- -about 2'mols for each mol of aniline, and the shellac used not exceeding, 50% by'weightof the aniline. 1

5. A fusible resin composition comprising the reaction product .of aniline with shellac and formaldehyde, the formaldehyde being present in an amount equivalent to at least mol for each mol of aniline, and the shellac used not exceeding 50% by weightof the aniline, the resin being thermosetting when it contains about 2 mols combined formaldehyde for each mol of aniline. n6. A fusible resin composition comprising an acid catalyzed shellac aniline formaldehyde resin in'whichthe formaldehyde is equivalent to at least'% mol for each mol of aniline, and the shellac used not exceeding 50% by weight of the aniline, the resin being thermosetting when it contains about 2 mols combined formaldehyde for each mol of aniline. I

'7. A fusible resin composition comprising an alkaline-catalyzed shellac-aniline-formaldehyde resin in which the formaldehyde is equivalent to at'least mol for each mol of aniline, and the shellac used not exceeding 50% by weight of the aniline, the resin being thermosetting when it contains about 2- mols combined formaldehyd for each mol of aniline.- a

8; A,heat,-:-set .infusible shellacaniline-formal dehyde resin in which th combined formaldehyde is equivalent to about 2 mols for each mol of aniline, and the shellac used not exceeding by weight of the aniline.

9. The. processwhich comprises reacting aniline with shellac and an aldehyde in a ratio of at least mol formaldehyde for each mol of aniline, the shellac not exceeding 50% by weight of the aniline, and adding "sufficient formaldehyde to combine with the aniline so that the total amount of.,.combined formaldehydeis. abouts mols for each mol of aniline, whereby'there produced a fusible thermosetting resin.

:10. The process which" comprises reacting shellac with an aromatic amine having an NH; group attached to a benzene ring in a ratiof not exceeding 1:2 by weight until a homogeneous composition is obtained, adding formaldehyde in an amount equivalent to at least mol for each mol of amine, reacting this mixture with--co0l-. ing to prevent a rapid rise in temperature, and after the reaction is no longer stronglyv exo-s. thermal, continuing the reaction und'er reflux until there is formed a fusible resin, the resin being thermosetting when it contains about 2 mols combined formaldehyde for each-mol of amine. 11. A fusible resin composition comprising the reaction product of an aromatic amine havingan NH: group attached to a benzene ring .with shellac-and an aldehyde, the ratio of aldehyde to amine being at least mol of aldehyde for each mol-of amine, and the shellac used not exceeding 50% by weight of the amine, the resin being thermosettingwhenv it contains'about 2 mols combined formaldehyde for each mol of amine. MILTON J. SCOTT..-; 

